At what cost. I'll bet your grandfather never tracked the cost of his workshop and time. Note too that the scenario is all hands on deck harvesting - skipping one day of harvest can (if there is worst case storm) cost your more in profit than a brand new combine.

If you have to pay someone labor the cost of keeping old machines running adds up a lot farther than most people realize. I know one construction company owner who in the 1990s worked it all out - all that 30 year old equipment that he was keeping running. Then he want to a dealer and signed a lease for $25,000/month, as he left the negotiations, reeling from the price tag, his account turned to him and said "you just saved yourself $30,000/month".

When you outsource support, that carries costs that are difficult to measure and not carried in the lease. Your "supply chain of business" just became less robust.

If you're in a business where a couple of days in lead time for repair can make or break a harvest, (1) having a repairs workshop (2) investing in tools you can reliably repair yourself is essentially an insurance premium that protects your harvest by placing its success squarely within the hands of the part most interested in success.

This "insurance" aspect is something that accountants reliably fail to account for, because it doesn't show up in any business ledger. But this way of thinking generally wins because it increases fiscal efficiency, while the side-effect of making systems more fragile is consistently written-off.

What farmers do is instead have a relationship with a mechanic (normally dealer) who has spares. If they can't fix it in a couple hours they bring a loaner you can use until they get it fixed. Simple problems can be done in an hour by your plan, but anything complex you are in the shop instead of the field for hours.

I'm hoping I get 30 years out of my sub-compact tractor. I'd hate to be an old man and have to buy another one on retirement income...

These things are not lawnmowers, and they should (if cared for) last.

I refused to even shop John Deere, the green paint tax is too high and on top of it you have all this subscription and computer B.S.